Method of and apparatus for converting x-rays into light for photographic purposes



(No Model.)

T. B. KINRAIDE. METHOD OFAND APPARATUS FOR CONVERTING X vRAYS INTO LIGHT POR PHOTOGRAPHIO PURPOSES.

Patented Dec.'21, 1897.

UNITED STATES PATENT nron.

THOMAS BURTON KINRAIDE, OF BOSTON, MASSACHUSETTS.

METHOD OF AND APPARATUS FOR CONVERTING X-RAYS INTO LIGHT FOR PHOTOGRAPHIC PURPOSES.

SPECIFICATION formingpart of Letters Patent No. 595,812, dated December 21, 1897.

Application filed January 15, 1897. Serial No. 619,309. (No model.)

To aZZ whom it may concern:

Be it known that I, THOMAS BURTON KIN- RAIDE, of Boston, county of Suifolk, State of Massachusetts, have invented an Improvement in Apparatus for and Method of Converting X-Rays into Light for Photographic Purposes, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

In the practical application of the so-called Roentgen or X rays to photography, especially in connection with surgical and pathological investigation, it is desirable and indeed essential that the photograph should be taken without extreme delay. In many instances the service of the cathode-ray is desired to locate a malformation or a foreign substance under circumstances when the life of the patient would be seriously jeopardized by fatigue, so that it is of the first importance that the results of the investigation shall be secured in the very shortest time possible. As at present devised, however, all X-rayapparatus requires considerable time of exposure, as well as various requirements as to favorable conditions, 850., so that not only is the practical use of this remarkable physical agent hampered, but it is restricted by the force of circumstances to those cases in which delay makes little difference.

It is the object of my invention to enable the operator to secure a superior photograph or skiagraph of the part desired in a much shorter time than has heretofore been possible.

The process at present employed makes use of a phosphorescent and fluorescent screen made of various materials which it is unnecessary to enumerate here, this screen being placed between the source of the rays and the photographic plate or medium for receiving the impression. The result is that the resulting picture is extremely unsatisfactory, due to the unevenness of the screen, it being impossible to make a screen with absolute evenness of thickness and density. The rays in passing through the thick portion produce very different effects on the sensitized; paper from that produced in passing through the thin portion, and the photograph has therefore a mottled and confused appearance. In-

asmuch as the practical value of these X-ray photographs depends upon the accuracy with which different densities of physical structure can be estimated therefrom, it is of the utmost importance that the tones or shades of the photograph should vary precisely as the densities of the different parts of the mediu m being photographed and through which the X-rays pass in making the photograph, and that the latter should not be distorted by reason of the uneven and necessarily mechanically imperfect screen. My invention meets this requirement perfectly. By my invention, moreover, the detail of definition in the resulting photograph is-remarkably accurate and delicate, approaching in this respect ordinary photographs.

According to my invention the photograph is made by rays passing through the medium beingphotographed and making its impression directly on the sensitized plate or paper, the rays, however, being clarified or reinforced by means of a fiuorescing converter placed beyond the sensitized plate. N 0 screen is used-that is to say, the rays are not passed through any fluorescent medium or screen interposed between the sensitized plate and the source of the raysbut upon passing through the object being photographed the rays are directed immediately upon the sensitized plate and their effect is augmented or reinforced, so to speak, by means of a fluorescent medium placed back of the plate.

My invention will be more fully apprehended in the course of the following detailed description thereof, reference being had to the accompanying drawings, illustrative of my improved method and the means for carrying it out.

In the drawings, Figure 1 is a top plan view of the apparatus for converting the X-rays, showing the same in process of photograph ing a hand placed thereon. Fig. 2 is a bottom plan view of the cover removed. Fig. 3 is a top plan view of the converting apparatus with the cover removed, showing a piece of sensitized paper in position thereon to receive the photograph. Fig. 4 is an enlarged vertical cross-section taken on the dotted line, Fig. 3. Fig. 5 is an enlarged detail in cross-section of the mirror-like ray-converting plaque or surface. Fig. 6 is a similar en tographby the old method, by my improved 1 method, and by my improved method when the photograph is held between the observer and the light.

The apparatus by meansof which I carry out my invention is extremely simple, and

for convenience of description is herein shown as comprising a base or body portion A, having reduced inset edges A and a central raised portion A and a cover B, comprising a rim or flange B,adapted to fit snugly down against the inset edges A, and a preferably flexible rest or closure B The rest or closure B may be pasteboard, ebonite, or any other thin and preferably flexible substance, and the entire cover, as well as the surfaces of the inset edges, will be stained or painted a dead black to effectually prevent all entrance of external light to the sensitized paper.

On the raised portion A of the baseI spread a convertingsurface O, secured thereon by any convenient means, as by a narrow frame 0, by tacks, or any other suitable means. As shown in Figs. 3, 4, and 5, this convertingsurface comprises a front 0 of translucent material-such, for instance, as celluloidthis material being extremely serviceable. on account of its translucent quality, durability,

lightness, and strength, and on. the under 1 side thereof is deposited a coating 0 of' some fluorescent salt, preferably calcium tungstate, put 011 in a paste or emboditetlin a gelatin or other vehicle, made as hereinafterdescribed.

Of course gelatin or any other translucent vehicle pervious to the rays may be used instead of the celluloid, inasmuch as its object is to support and protect theexceedingly expensive and easily-destroyed calcium tungstate which I prefer to use as the fluorescent medium. certain instances to-use the calcium tungstate or other chemical constituent without any separate front a, and I have shown this structure in, Fig. 6, inwhich 0 denotes a gelatin vehicle in which the chemical is thoroughly mixed, and is then rolled out into a thin even sheet and allowed to harden, and is subsequently coated on its upper surface witha coating 0 of white varnish, collodion, or other protector, providing a translucent surface for the fluorescentcoating or compo,- sition.

A converting-surface such as I have last mentioned may be readily made of gelatin, placed on aglass surface polished with French chalk, allowed to harden, and then stripped off, as is commonly done incertain well-known processes in photography.

I am aware that it has. been proposed in I have found it desirablein r ordinary photography ,to provide the usual sensitive-plate with a fluorescent layer between the glass and the emulsion for the purpose of preventing halation and solarization, and I disclaim the same, my invention having nothing to dd with photography, as the term is popularly understood, bu t, on the con-.

trary, having to do with the X-rays producing photographs, or, more properly, radio- 1 graphs, by transmitted light or rays depending upon the atomic weight of the object through which the rays pass. Moreover, by the so-called flourescent material used in the emulsion on the glass plate mentioned in the last paragraph was meant material flucrescent in the sunlight, whereas the X-ray fluorescence with which my invention has to do is not responsive to light-11 e., to sunlightthe word fluorescence being, in fact, incorrect or atleast misleading for this reason, inasmuch as it had already been appropriated by physicists before the Roentgen discoveries to mean something elsenamely, a certain responsiveness tolight. The material proposed to be used in the emulsion was quinine, the object being to do away with the actinic effect of certain rays of the spectrum, whereas in myinvention quinine would be entirely useless, with noefiect whatever, the invention having nothing to do, with the spec trum or with light rays and the object being 7 to increase or rather occasion actinic effect. While I have described above the preferred details of the mechanical embodiment of my invention, yet I do not intend in any way to limit myself thereto, inasmuch as my invention may be carried'out in a wide range of mechanisms. It is obvious that the form of almost any of the usual plate-holders and :roll-holders commonly used in photography f is adapted by very slight changes to the purposes of-my invention. '1 The particular frame or means of supporting and utilizing my improved converter or Converting-surface is a subordinate part of my invention, and therefore I do not restrict myself in any respect thereto.

The novel method by which I proceed to take the improved photograph or cathode picture andin which I use my improved apparatus, above described, is as follows: The Crookes tube or other source of the X-rays is set u pin front of the part or substance which :it is desired to photograph, and for purposes of illustration we will suppose that this is a human hand, and the apparatus, containing a 1 sheet of sensitized paper P, having its sensitized surface turned against the converter 0, as shown in Fig. 5, is. placed against the hand, "preferably with suff cient pressure to spring the flexible closure or rest B in immediate contact with-the paper. The rays pass through the'hand and act uponthe sensitized paper, which maybe superiorbromidpaper or, other extremely sensitive paper or plate, acting thereuponin theusual manner, so that if my apparatus were not used the appearance of ICC IIC

" Fig. 7.

For the purposes of this patent it is unnecessary to enter into a discussion of whether this action is chemical or physical. The effect is that the same length of exposure which is given to produce the indefinite and obscure lower half of Fig. '7 produces by my method and apparatus the superior and definitelydetailed upper portion of said figure. In other words, the detail of definition is heightened and effects of the lights and shades are strongly reinforced or perhaps exaggerated, a further result being also that whereas in the ordinary cathode picture irregularities in thickness and contour of the bones are not brought out, this being clearly shown in the lower half of Fig. 7, by my process the photograph clearly represents all the details, not only of profile shape, but of differences in thickness or general shape, and also another remarkable result is that the picture or photograph which when viewed by reflected light appears as shown in the upper righthand part of Fig. '7, in which the flesh of the hand is scarcely discernible in the slightest degree, yet when viewed by holding the photograph between the observer and the light the details of the flesh are clearly discernible, as is shown in the illustration of the forefinger and thumb, Fig. 7.

Not only is the force or effect of the X-rays on the photographic film or sensitive substance increased or reinforced by my method, as above explained, but, what is perhaps of still more importance, the photograph represents with absolute accuracy the variations of homogeneity of the tissue or substance being photographed and whose internal composition and arrangement it is desired to study. This is of extreme value in studying pathologic modifications. Furthermore, in order to get as good results as have heretofore been attainede that is to say, such results as are indicated in the lower part of Fig. 7it is not necessary by my method to give nearly the length of exposure which is at present required, thereby enabling the physicist or surgeon to utilize this remarkable agent in extremely critical cases where otherwise its use would have been unwarranted.

My method as above outlined directs the X-rays against an absolutely even and uniform surface of the convert-ant or fluorescent material, the rays presumably penetrating this substance to a uniform extent, and thereby obviates all the disastrous and unscientific results of the old processes, which requiredthe X-rays to pass through a screen of necessarily unequal density and irregular surface at one side or the other.

By the term fluorescent surface or converter, as herein used and employed in the claims, I do not restrict myinvention'to a technically so-called fluorescent salt as constituting the active ingredient, nor to any actual conversion or transformation of the X-ray, inasmuch as I intend to include any chemical, crystal, or other substance which produces the effects at present popularly denominated in this connection as fluorescence by the journals and papers of the day, and it will be understood also that I use the term X- ray in its popular sense, to denote the inductive waves, or it may be violet or ultraviolet waves or longitudinal Vibrations,which are variously termed cathode rays, anode rays, the. by investigators, and which is presumably a condition of electric force, ether, or other manifestation of light.

Having fully described my invention, what I claim, and desire to secure by Letters Patent, is-

1. The herein-described method of taking an X-ray radiograph, which consists of inter-y posing the object to be copied and a photo- 1 graphic plate or substance between the source of the X-rays and a surface or converter which transforms the invisible X-rays into light,sub i 0o stantially as described.

2. The herein-described method of taking an X-ray radiograph, which consists of placing a sheet of photographic substance upon an X-ray-convertingsur ace, and interposing between said photographic substance and the source of the X-rays the object to be radiographed, substantially as described.

3. An X-ray apparatus comprising a base, and a plane surface thereon translucent to X- rays, said surface having a coating or composition of material capable of transforming the invisible X-rays into visible actinic light, substantially as described.

4:. An X-ray apparatus comprising a base, a translucent surface thereon, said surface having a coating thereon of material capable of transforming the invisible X-rays into visible actinic light, and a removable cover therefor, substantially as described.

5. An X-ray apparatus comprising a base, a translucent surface thereon, said surface having a coating thereon of material capable of transforming the invisible X-rays into actinic light, and a cover therefor, said cover having a flexible rest, substantially as described.

6. A fluorescent surface for use in X-ray work comprising a layer of non-sensitive material translucent to the X-ray, and a layer containing a substance united therewith capable of transforming the invisible X-rays into visible actinic light, substantially as described.

ing a gelatin vehicle and a substance carried thereby capable of transforming the invisible X-rays into visible actinic light, substantially I 5 as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses.

THOMAS BURTON KINRAIDE.

\Vitnesses:

JOHN C. EDWARDS, GEO. I-I. 1VIAXWELL. 

